A spontaneous notion is enough to get things going – just a gaggle of notes, really. In his fully improvised solo work, Keith Jarrett doesn’t need much more than a sketchy vamp or a hint of a riff to ignite the ever-shifting parade of melodies he inevitably conjures. It’s a babbling brook approach. The water is essential, sure, but once its moving, the momentum is the most inviting aspect of the experience. Where’s it going to wind up? Splashing rocks, soaking leaves, eddying into a pool created from pure fluid force? Possibilities abound. Through 15+ solo albums since his 1971 recital debut Facing You, Jarrett has become uniquely eloquent at concocting themes from his rich imagination and – perhaps more importantly – connecting them in rhapsodic episodes. In a word: flow.

A Multitude of Angels catches the pianist in both a place of vulnerability and strength. Comprised of four CDs from four concerts in four Italian cities, these unedited 1996 improvisations were recorded right before a major career break due to his extended bout with chronic fatigue syndrome. He bounced back from its pernicious clutches a few years later, but these days he chooses to break his virtuosic solo sets into discrete sections rather than sustain the uninterrupted sense of adventure that earned him a global rep via live masterpieces such as Bremen/Lausanne and The Koln Concert.

This current approach hasn’t played havoc with the key elements of Jarrett’s aesthetic boilerplate, though. Comparatively recent discs such as Rio and Paris/London: Testament brim with passages that range from two-fisted frenzy to one-fingered poignancy. Using the entire instrument to voice the details of his overtly emotional music has always been a Jarrett forte. A full blush of broad strokes and nuances comprise his work on Angels, so I thought it might be helpful to list a few of the maestro’s cornerstone artistic elements and point out their agency here.

DELICACY: Jarrett sat down Torino, Italy and, at a courageously limpid tempo, began to sketch an extended musing that consistently folded inward with enough commitment to be deemed a public meditation. By the time he whittled away his need for the middle register and headed up to trillville, he’d reached the kind of composure that only needs a note or three to speak its mind. His music has long been built on sensitivity. At its most dubious, far too much so. But as his right hand ekes out a series of exquisite glisses that prove a pivot point to the feistier ardor to come, he reminds us just how much terrain he can convincingly traverse while illustrating the power of grace.

EXPRESSIONISM: Frenetics aren’t a Jarrett staple but he’s certainly a fan of the high-flying vigor that reaches out and grabs an audience. His second improv in Modena takes off with a small storm of action that that dodges the dissonance but tips a hat to the cagey delirium Cecil Taylor so judiciously employed in ‘60s. As his fragmented phrases land on top of each other and the pianist determines the architectural logic in real time, a hurtling momentum arises. This skyscraper is built on shards, but its integrity is obvious.

CATHARSIS: Repeat a riff or lick with just the right volition and there’s a good chance you’re going to enhance its meaning with every new go-round. Blues musicians know all about it. About 10 minutes into “Verona 2” Jarrett reaches a point where his Morse Code repetition of one note starts to blossom into a left-hand motif that brings a hammerhead force front and center. A few more minutes and it’s a Steve Reich barrelhouse scenario – spilling, building, intensifying. The pianist takes it farther than others might – for a moment or two it seems like the soundtrack to an OCD episode. But by the conclusion the extended pounding makes way for a breakthrough. Like Van Morrison throttling the phrase “streamline promenade” during hell-raising live performances of “Moonshine Whiskey,” Jarrett wallops the instrument until the mountaintop has been reached.

TRANSCENDENCE. He poured out the passion in two extended Ferrara pieces, but the pith of this untitled encore winds up speaking volumes. Touch is a Jarrett hallmark – he can have a single note resonate in a variety of ways – and this bittersweet sign-off has the feel of a drone. He feathers the keyboard, and with one note bleeding into the next, it almost sounds like a horn player is center stage. An abstract spiritual with a folkish, vaguely Celtic, aura.

In his notes for the box set, the man who once said he slept under the first real piano he got for his birthday as a child because he was so smitten with its possibilities, reports that the “angels” of the album title are many – the audiences, instruments, concert halls, and energy that got him through these shows all conspired to reach what he deems a “pinnacle” of his career. Jarrett’s high points are many, so as far as pinnacles go, maybe it is, maybe it’s not. But a couple things seem irrefutable. The resourcefulness and vision of this music is obvious, and these luminous excursions repeatedly cut right to the heart of the matter, even when they take the long way ‘round.

There’s no lack of great guitarists in country music. Start with Merle Travis, veer over to Chet Atkins, make way for Speedy West & Jimmy Bryant, and you’ll still have plenty of killer string-players left to discover. From grace and nuance to speed and authority, their pickin’ usually brings out the lyrical character of the song at hand while helping sell its emotional clout. Absorb what Atkins does with James P. Johnson’s “Carolina Shout” and you’ll hear how a delicate statement of melody, flecked with a handful of witty fills, can be tied up in a swinging little package.

It probably won’t surprise longtime fans, but John Scofield has a way with twang, too. It’s an opinion that continuously unfolds on Country For Old Men, a romp through tunes associated with Hank, hollers, and honky tonks. Somewhere in the middle of “Mama Tried” the 64-year-old bandleader reminds us that prioritizing lyricism is a forever winning approach when it comes to broaching eloquence, and that pacing is an expert’s game.

In the first verse, Scofield starts off shadowing Merle Haggard’s melody, and from “doin’ life without parole” to “her pleading I denied,” he makes it seem like he’s fully happy to color inside the lines. Then, ka-boom, it’s lift-off time. As drummer Bill Stewart, bassist Steve Swallow and keyboardist Larry Goldings flip Hag’s steady clip-clop rhythm into something much sleeker, Sco roams the back 40, blowing a string of idiosyncratic phrases and adroitly linking ‘em together. Merle loved to swing, too – he was a Bob Wills freak, after all – and it genuinely seems there’s a legit nexus being forged between the two as the guitarist messes around with the singer’s melody.

This all works because Scofield is a song guy. From his earliest albums on, originals such as “Holidays” and “Fat Dancer” were the kind of improv vehicles that were easy to hum along with. As the decades flew by, that skill was sharpened. Quiet’s “Away With Words” and Works For Me’s “Not You Again” are earworms par excellence. By the time he started putting his spin on Ray Charles (check the boo hoo version of “Crying Time”) and the gospel canon (see the bouncy prayer of “I’ll Fly Away”), an approach had been fashioned. Country music has been in his head for a while, too. In 2007 he added extra a dollop of grace to Charlie Rich’s “Behind Closed Doors.” Personally, I wanted to hear more Nashville notions from him right then and there.

Scofield’s known as burner; in the last 15 years, he’s spent time reinvigorating the jam band formula and proving how cogent some psychedelic explorations can be. Country For Old Men is flecked with firecrackers; it has a “Red River Valley” that conjures Booker T & the MGs playing at CBGB, a straight-up frantic “I’m So Lonesome I Could Cry,” and an “Wildwood Flower that might give A.P. Carter heart palpitations – hard-driving stuff. But as he did on Rich’s chart-topping ode to lust, here Sco shows us just how strong his ballad game is. Old Men finds him on a George Jones jag, racking up three gorgeous tearjerkers by the country icon. “A Girl I Used To Know,” approximates Possum’s jukebox melisma, deploying all those swoops and slurs in the “I won’t be-ah-egg you not to go” line. As “Mr. Fool” closes out, the guitarist alludes to Freddie King – launching single-note exclamations everywhere. And you can certainly feel the shot ‘n’ beer woe at the heart of “Bartender’s Blues,” the gin mill waltz that James Taylor laid on Jones’ plate in the late ‘70s. Mix this old-school beauty with the drama Scofield brings to Dolly Parton’s “Jolene” and the cunning of his flow on Shania Twain’s “Still The One,” and a through-line emerges: lilt and whimsy are essential to his toolbox these days. No wonder he closes with a 30-second tintype refraction of “I’m An Old Cowhand” that manages nods to both Sonny Rollins and Roy Rogers.

Tricky business, this classical/jazz confluence. Bridging a chamber aesthetic and a bandstand vibe risks impairing each element. No question about one thing, though: on imaginist (Panoramic/New Focus), the coherence between respected string ensemble JACK and feisty improv group The Le Boeuf Brothers is lacking naught. Regardless of whether the music fully convinces you, the synergy is sufficient to create its own pleasures. Performance-wise, the Le Boeufs and JACK pull off a nice collabo.

“It” is a union of strings, reeds, and rhythm that’s meant to parallel a reader’s experience of traversing a narrative. A rich suite that boasts both prologue and epilogue, imaginist finds composer-pianist Pascal Le Boeuf and his sax-playing brother Remy alluding to Russian poetry gambits, speculating on the calculated risks of the exquisite corpse process, and spinning one of Kafka’s existential tales so that it has antecedents in both Prokofiev’s Peter and The Wolf and Ken Nordine’s Word Jazz. A somewhat dizzying venture, indeed.

The sound of the two groups uniting is sumptuous. Moving from vivid instrumental passages that feature saxophonist Ben Wendel to an extended narration of Kafka’s “A Dream,” Pascal’s rigorous pieces do everything they can to utilize the breadth of hues a double ensemble can conjure. Whether they’re scurrying through “Alkaline” or ruminating in “Foreshadow,” the tone is compelling. Wendel’s hollow cry in “Prologue” conjures the radiance of Jan Garbarek on Keith Jarrett’s Abour Zena.

Actor Paul Whitworth augments these textures with a narration of “A Dream” that gives the eerie graveyard reverie a whimsical slant. There are moments where it seems a tad too puckish, the music undercutting the grim story line; but ultimately Le Boeuf’s compositional change-ups are fetching. That’s certainly true on “Pretenders,” where the jazz and classical union couldn’t be any more balanced. All this elaboration is a break from the Le Boeuf’s somewhat frothy music of the past, and it brings a welcome gravitas to their growing songbook.

God is in the details. When I started truly focusing on Kris Davis’ 2011 solo date Aeriol Piano, each of the melodies, and then each of the phrases, and finally each of the notes seemed to accumulate additional meaning. A case could be made for this being true in lots of jazz, but there’s something in Davis’ music that underscores it. The Brooklyn pianist invests deeply in the character of both boom and plink – you can hear it as she courses through the 16 duets with eight instrumentalists on Duopoly. Whether she’s goosing a Billy Drummond tom-tom thud or refracting a Tim Berne sax screech, part of the glory lies in the music’s textural minutia.

Take, “Surf Curl,” a fizzy ode to fluidity made with Julian Lage. Like half the album’s tunes, it’s a written piece that Davis and partner interpret at will. As each player bounces ideas off the other, the macro gathers into a forceful wash while the micro blossoms with riveting singularities. It’s a tack that brokers a foreground/background blur, and it happens repeatedly as this parade of partners determines how to coincide. The power of the pregnant pause has never been as eventful as when Davis and Craig Taborn momentarily suss out their trajectory during the opening section of “Fox Fire.”

Duopoly’s second half is all about pure improv, yet each off-the-cuff gambit is architecturally sound enough to satisfy design-wise. “Marcus Gilmore” entices with a fluid exchange around a squirrly motif, and “Don Byron” is just as bewitching as the pair’s clarinet-piano pas de deux on “Prelude To a Kiss” from the written section. Even as “Bill Frisell” ends the disc in a ghostly haze, it’s hard to decide what to focus on, the aura or the ingredients. Watching it unfold on the album’s accompanying DVD of the session makes it that much more engaging. A big win/win those who appreciate process.